The present invention relates to an improved architecture for jet aircraft which uses onboard electric power in combination with a reduced bleed air system to power aircraft systems.
Many of today""s aircraft use the extraction of thrust engine compressor bleed air to power the aircraft cabin and cargo ventilation system, the environmental control system (ECS), the wing and cowl anti-ice system and the engine start system. The extraction of engine cycle compressor core bleed air places a significant penalty on the engine cycle, reducing engine efficiency. Much of the power inherent in the extracted bleed air is purposely wasted in the bleed air control and distribution system to ensure that the hot bleed air conforms to aircraft material limits, before it is delivered to the load system. The bleed air extraction and distribution equipment required to use engine bleed is expensive to purchase and install, and relatively unreliable. Additionally, the start system hardware is used only for engine start, remaining idle for the majority of a flight.
Accordingly, it is an object of the present invention to provide an improved aircraft architecture which relies upon electrical power to operate aircraft systems instead of engine bleed air.
The foregoing object is attained by the aircraft architecture of the present invention.
In accordance with the present invention, an aircraft is provided which has a first engine, a first gearbox associated with the engine, a first starter/generator associated with the gearbox, and a first motor drive connected to the first starter/generator for providing the starter/generator with electric power to start the first engine and to receive electric power from the starter/generator after the engine has been started to operate electrically driven systems onboard the aircraft. The aircraft preferably further has at least one other engine which has a gearbox and a starter/generator associated with it and at least a second motor drive connected to the starter/generator. The electrically driven systems operated by the motor drive(s) include an environmental control system, a wing anti-icing system, an aircraft control system, and the aircraft fuel system.
The aircraft also includes an auxiliary power unit for supplying electrical power to at least the first motor drive for initiating operation of the first engine. The auxiliary power unit has a starter/generator and a motor drive connected to it, which motor drive may be connected to a battery for starting operation of the starter/generator and the auxiliary power unit.
A method for providing starting power to an aircraft and for generating electrical power to operate aircraft systems is provided. The method broadly comprises providing a first starter/generator connected to an engine and a first motor drive connected to the starter/generator, supplying electrical power to the first motor drive, conditioning the electrical power with the first motor drive and delivering the conditioned electrical power to the first starter/generator, and motoring the engine with power from the first starter/generator. The method further comprises operating the first starter/generator in a generate mode after the engine has started and supplying electrical power from the first starter/generator to a second starter/generator to start a second engine and to the first motor drive. The first motor drive utilizes the electrical power received from the first starter/generator to operate electrical systems onboard the aircraft.
Other details of the aircraft architecture with reduced bleed aircraft secondary power system and the method of the present invention, as well as other objects and advantages attendant thereto, are set forth in the following detailed description and the accompanying drawing.